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Biomedical subjects

L Mejean

Publications and source records attributed to L Mejean.

At least 19 recordsLinked to original sources
PubMed2005

Behaviour of dioxin in pig adipocytes.

Due to their lipophilic properties, dioxins can be integrated into the lipidic vacuole of adipocytes (fat cells). The aim of this study was to determine the kinetics of incorporation and release of 3H-labelled palmitic acid and 14C-labelled 2,3,7,8-TCDD in isolated adipocytes from pigs. The incorporation of 2,3,7,8-TCDD and palmitic acid was found to be concomitant under conditions of lipogenesis, under the effect of increasing quantities of insulin and in the presence of glucose. Release of these two compounds was found to be dependant on a lipolytic agent (epinephrine). These results suggest the risk of a strong increase of 2,3,7,8-TCDD, induced by lipolysis, in the blood of animals or humans previously exposed to this dioxin.

Adipocytes↗
PubMed2001

The cholesterol-lowering property of soybeans fed to rats is related to the fasting duration.

Numerous factors affect plasma cholesterol and, therefore, represent potential interferences with the specific effects of diet on lipid metabolism. After casein intake, serum cholesterol levels depend on many experimental conditions in rats, such as the type of casein, the presence or absence of cholesterol in the diet, the age and strain of rat, the diet composition, the nutritional status. The effect of fasting duration on selected parameters was studied in adult male Wistar rats fed a 20% casein and 1% cholesterol-based diet. No changes were observed in total serum, lipoproteins-B and HDL cholesterol and in triglyceride values after an 8 h-fast compared to non-fasted animals. A significant decrease was induced in total and lipoproteins-B cholesterol with a 12 h-fast. A prolonged fast resulted in a significant decrease in these parameters and in triglycerides and in HDL-cholesterol levels. Fasted animals fed heated soybean meal instead of casein did not display a marked decrease in serum lipids. It appeared that the fasting effect was more marked in animals fed casein than in animals fed soybeans. These results showed the importance of experimental conditions such as nutritional status of animals when blood samples are taken in studies of the hypocholesterolemic effect of soy protein compared to casein.

Animals↗
PubMed1996

[Chronobiology, nutrition and metabolism].

The "nutrition" function is fulfilled by a succession of physiologic actions of which the first is eating and the last is the intracellular metabolism of nutrients. These actions involve not only sensory processes subjected to neurocentral regulation but also peripheral metabolic, and hormonal processes. The physiologic "nutrition" function involves a number of parameters for which fundamental rhythms have been demonstrated, such as eating behaviors, intra- and extracellular metabolisms, hormone secretions and their effects on target organs, and use of food and nutrients. Each of these rhythms can be demonstrated under physiologic conditions but can be modified by environmental factors (temperature, light, seasons, physical and mental activity), disease states (many diseases can produce profound alterations in nutritional regulation processes), and drugs. Interactions between these rhythms also exist; for instance, eating behavior rhythms can be modified by sociocultural pressures and this can, in turn, modify the fundamental rhythms of biologic parameters. The unit of time that allows the study of these rhythms varies: in addition to circadian and ultradian rhythms, weekly (cisaseptian) and annual (circannual) cyclical changes should be taken into account when investigating human nutrition.

Adolescent↗
PubMed1995

Relationships between macronutrient intake, handicaps, and cognitive impairments in free living elderly people.

It is still unknown what if any relationships exist between intake of macronutrients by the elderly, and their functional or cognitive handicaps, particularly for free living elderly people. We investigated 226 men and 215 women, aged 65 or more, free living and in good health. They were randomly selected in the département of Bas-Rhin, after stratification for age, sex and residence (rural or urban). Handicaps and cognitive functions of each subject were assessed with the Géronte scale and the Mini-Mental State Examination (MMSE), respectively. Food intake was measured by a three-day record. A multiple correspondence analysis concluded that functional parameters and macronutrient intakes were rather independent. The relationships found were detailed by a backward stepwise logistic regression. In men, alcohol intake was associated with an improvement in functional and cognitive parameters, and polyunsaturated fatty acids with the capacity to move outside the home. In women, lipid intake increased the MMSE score. Overweight in women was linked with better functional and cognitive performances, and in men with the capacity to move outside the home. In both sexes, age worsened the score of functional and cognitive parameters. In conclusion, macronutrient intakes and functional or cognitive parameters were found to be mutually independent; this suggests that macronutrient deficiencies are of little importance in the worsening functional or mental autonomy of the elderly. The relationships found between functional variables and alcohol or polyunsaturated fatty acid intakes in men, and lipid intakes in women, and overweight in both sexes might evidence a better state of health.

Aged↗
PubMed1993

[Effects of treatments (heat and fermentation by Rhizopus oligosporus sp-T3) of sweet white lupin seeds on certain factors of its nutritional use].

For improving the nutritional value and functional properties of sweet white lupin (SWL), a solid fermentation process using Rhizopus oligosporus was developed for the preparation of lupin products. A comparison of the effects of soaking + thermal treatment and fermentation was made from 3 lupin products: non-treated lupin seeds (SWLnt), heated lupin seeds (steamed at 100 degrees C for 30 min) (SWLh), and fermented lupin products (SWLf) from SWLh on chemical characteristics and protein efficiency ratio (PER) in rats. The major effect of soaking and thermal treatment is a loss of protein solubility and available lysine (from 3.02 +/- 0.18 g/16 g N to 2.3 +/- 0.25). Fermentation leads to a modification, of amino acid composition and to an increase in available lysine compared to heating (2.90 +/- 0.12 g/16 g N). The nutritional quality of SWLnt is low (PER = 0.83 +/- 0.09), thermal treatment decreases it (0.58 +/- 0.18) and fermentation compensates heating effect (0.74 +/- 0.25). It is suggested that the modifications of nutritional quality depends on the availability of lysine rather than on the variations of the levels of other amino acids.

Fermentation↗
PubMed1991

Effects of breakfast-size on short-term memory, concentration, mood and blood glucose.

Effects of breakfast size on blood glucose, mood, short-term memory and concentration were assessed in 319 adolescents (age 13-20 years) in real-life setting. Mean energy increase of 63% over habitual breakfast had no effect on blood glucose or late morning mood. High energy intake from breakfast had a beneficial effect on immediate recall in short-term memory evaluated on the whole sample. However, concentration appeared to be impaired by a high caloric breakfast. There were no differences in the studied parameters according to energy supplement size. The present results are consistent with suggestions that meal size supplement has an effect on cognitive function.

Adolescent↗
PubMed1991

Effects of the nature of dietary proteins, lecithin and methionine on rat plasma lipids.

In order to study the complex interrelationships between on the one hand, dietary proteins, lecithin and methionine and, on the other, blood cholesterol and triglyceride levels, groups of .10 rats were fed for six weeks with diets only differing by the nature of proteins which comprised 10% of the diet. These diets were composed of egg white, heated soybean flour, casein, heated soybean flour supplemented with 1% methionine, or with 4% of the lipids replaced by soybean lecithin, heated 5-day germinated soybean supplemented or not with 1% methionine and casein with 4% of the lipids replaced by lecithin. Egg white caused no change in blood cholesterol compared to heated soybean meal (0.955 +/- 0.18 vs 0.83 +/- 0.14), but caused a significant increase in blood cholesterol levels compared to casein (0.955 +/- 0.18 vs 0.81 +/- 0.11 g/l). No effect was found on blood triglycerides levels. Lecithin caused no change when it partially replaced lipids in the soybean or casein diets thought it increased triglycerides with the casein diet (1.16 +/- 0.31 vs 0.84 +/- 0.24 g/l). Supplementation of the heated soybean diet with 1% methionine led to an increase in blood triglycerides (0.85 +/- 0.26 vs 1.18 +/- 0.34 g/l). After germination, this effect disappeared. The effects of the type of protein, partial replacement of dietary lipids by lecithin and supplementation with methionine are discussed.

Animals↗
PubMed1990

[Effects of alginates and sodium carrageenates mixed with soy proteins on the coefficient of protein efficiency].

Male 21 d-old Wistar rats, were fed for 4 wk with diets containing casein or soybean proteins (10%) with 0.5, 1, 2 or 3% sodium alginate or sodium carrageenan or without any alginate or carrageenan. Daily protein intake and weight gain of casein-fed rats were not significantly different (P less than 0.05) from those of rats fed soybean meal with alginate, whatever the dose received. Rats fed 3% carrageenan in soybean meal had significantly higher feed intake than that of rats fed casein. At the levels studied, alginate had no effect on the Protein Efficiency Ratio (PER), but carrageenan did. The addition of increased quantities of carrageenan to soybean meal followed by heating the mixture led to a progressive and significant decrease in PER at all levels of carrageenan compared to casein feeding. The addition of 3% carrageenan to heated soybean meal, corresponding to 0.62% of meal diet, led to a significant decrease in PER. These results confirm the precipitating role of carrageenans on proteins.

Alginates↗
PubMed1989

Dietary intake and other determinants of blood vitamins in an elderly population.

The relationships of diet, plasma lipids, age, gender, ponderal index, cigarette and alcohol consumption, drug use and infections to blood concentrations of retinol, beta-carotene, alpha-tocopherol, ascorbic acid and vitamins B1, B2, B6 status were studied among 291 men and women aged 60-82 years. Statistically significant correlations between dietary intake and blood indicator levels were found respectively for beta-carotene, alpha-tocopherol, ascorbic acid, vitamins B2 and B6, but not for retinol and thiamin, when the effects of other parameters were controlled. The main other determinants were cigarette consumption which had a negative effect on status for retinol, beta-carotene, alpha-tocopherol, ascorbic acid and vitamin B2; alcohol consumption for retinol, vitamin B6 (positive effect on status) and beta-carotene (decrease of plasma level); plasma lipids and use of hypolipaemic drugs for fat-soluble vitamins; ponderal index for beta-carotene and vitamin B6; gender and use of antibiotics for ascorbic acid. The apparent relation between gender and level of retinol, beta-carotene, alpha-tocopherol and vitamin B6 status was not any more significant after adjustment for alcohol or cigarette consumption. Tobacco and alcohol appear to be associated factors which should be controlled for in studies investigating relations between these vitamins and diseases influenced by smoking and drinking habits.

Age Factors↗
PubMed1989

[Nutrition behavior in adolescent students (15-19 years of age) in the Nancy metropolitan area. A comparison with the recommended nutritional intake of the French population].

This paper describes the food behavior of 495 adolescents (15-19 years old) sample living in Nancy (France). The results are compared with the Recommended Dietary Allowances (RDA) for French adolescent population. The RDA are not satisfied for important percentages of girls for the daily energy intake (26.3% of girls have allowances less than 30% RDA), for the calcium intake (28.7% of girls have allowances less than 40% RDA), and for the protein intake (17.6% of girls have allowances less than 20% RDA). Lipids consumption is excessive (19.9% of boys and 23.4% of girls have allowances greater than 20% RDA) and energy intake from breakfast are low (25% of adolescents provide less 10% of daily energy intake by breakfast) for all these teen-agers. These results confirm the data observed in two others studies concerning the food behavior of French adolescents.

Adolescent↗
PubMed1988

Circadian and ultradian rhythms in blood glucose and plasma insulin of healthy adults.

The circadian and ultradian variations of blood glucose and plasma insulin have been characterized individually and as a group phenomenon in five healthy young adults studied while adhering as closely as possible to their usual routine of sleep, activity, meal content and timing. Three complementary methods were used to analyze the data: displaying raw data as a function of time; cosinor method according to Nelson and Halberg; and time series analyses as proposed by De Prins and Malbecq. The subjects were studied in the laboratory and their life routine were controlled, but very close to that of their habitual routine. They had mainly ultradian rhythms of blood glucose (mainly about 6 hr) and circadian rhythms of immunoreactive insulin (I.R.I.). Blood glucose ultradian rhythms seem to be mainly but not exclusively mealtime dependent, while I.R.I. circadian rhythms appear to be primarily endogenous in origin. Therefore, the role played by insulin in the control of blood glucose levels seems to be programmed on a circadian basis rather than by a time independent feedback phenomenon as postulated by the conventional homeostatic hypothesis. The advantage of this chronophysiologic approach is to consider circadian rhythms of both I.R.I. and insulin effectiveness as an adaptive phenomenon able to maintain blood sugar changes in the ultradian domain of rhythms.

Activity Cycles↗
PubMed1984

[Effect of a 36-hour fast on blood glucose and insulin responses to the glucose stimulus in the normal subject].

The authors show that it's been able to perform an oral glucose tolerance test on subjects after an 36 hrs 'fasting, providing that a feeding with 250 g of carbohydrates has been brought on the three days before fasting. Three oGTT were performed on 10 normal subjects and carried out as follow: the first after a 3 days' period of usual food intake, the second after a 36 hours 'fasting, the third after a new three days' period with the usual food intake. The first and the third glycemic and insulinemic responses to oGTT are not significantly different. However, after the third period, weight, triacylglycerolemic rate and fasting blood sugar levels are still significantly below the initial values.

Adult↗
PubMed1984

[Plasma glucose and C-peptide after ingestion of sucrose and starch in controlled insulin-dependent diabetics. Importance of glucose availability].

Oral tests using 50 g of sucrose and 100 g of white bread were carried out in ten insulin-dependent diabetics (four with signs of residual B-cell function and in six without). Plasma glucose and C-peptide (CPR) were estimated during the 180 minutes after ingestion. After bread intake, plasma glucose increase was significantly delayed (30 min.). Hyperglycemia (greater than 2.5 g/l) lasted significantly longer after bread then after sucrose ingestion. Blood glucose decreased more quickly in subjects with residual B-cell function than in subjects without. CPR was not significantly modified by either of the carbohydrate loads. In the controlled insulin-dependent diabetic the hyperglycemia observed results from the ease of carbohydrates hydrolysis and from the amount of available glucose. The role of fructose seems weak in the case of sucrose because its conversion to glucose would be minimized in the presence of metabolic normalization as indicated by a well controlled blood glucose.

Adolescent↗
PubMed1983

Fenofibrate and human liver. Lack of proliferation of peroxisomes.

In rodents fenofibrate shares with other triglyceride-lowering agents the potential to increase the liver peroxisome population. It was therefore of interest to look for this effect in hyperlipoproteinemic patients receiving this drug. Light and electron microscopy of liver biopsies from a group of 10 patients treated with fenofibrate and from another group of 15 receiving diet only, show no morphological difference between both groups. In contrast with the rodent data the morphometric study reveals no significant changes in the number (fenofibrate group: 7.96 10(10) cm-3; group receiving diet alone: 8.41 10(10) peroxisomes/cm3 of liver tissue) or in the size (fenofibrate group: Diameter = 0.53 +/- 0.07 micrometer--group receiving diet alone: 0.50 +/- 0.06) of peroxisomes. The difference between our results and those obtained consistently in rodents may be due to the relatively low dose in man and/or a species-dependent difference in enzyme content of liver peroxisomes, itself related to an apparent difference in the way in which lipids are handled.

Adult↗
PubMed1983

Plasma glucose and insulin responses to oral glucose in nonobese subjects and patients with endogenous hypertriglyceridemia.

Plasma glucose and insulin responses to a 50-gm oral glucose challenge were determined in 396 nonobese subjects: 220 patients with endogenous hypertriglyceridemia and 176 normal persons. These groups were further subdivided on the basis of relative body weight: 1.0-1.1 and 1.1-1.2. Patients with endogenous hypertriglyceridemia whose obesity index was between 1.0 and 1.1 had significantly increased plasma glucose (more than 25%, P less than 0.001) and insulin (more than 18%, P less than 0.01) responses. Similar findings were also observed in patients with endogenous hypertriglyceridemia whose index of obesity was between 1.1 and 1.2, ie, there was a 25% increase in the plasma glucose response (P less than 0.001) and a 37% increase in the plasma insulin response (P less than 0.001). Thus, endogenous hypertriglyceridemia can occur in nonobese individuals, and these patients have an increase in their plasma glucose and insulin responses when weight-matched with nonobese normal subjects.

Blood Glucose↗
PubMed1983

[Apoprotein B in high density lipoproteins: variations according to the type of hyperlipoproteinemia].

Two techniques for the separation of high density lipoproteins are compared: ultracentrifugation and concanavalin A precipitation. There is a significant correlation for the high density lipoproteins cholesterol levels found by the two techniques (r = 0.66, p less than 0.001). Nonetheless ultracentrifugation gives higher values than precipitation. When the ultracentrifuged high density lipoproteins fraction was precipitated with concanavalin A, a highly significant correlation was found between the amounts of apoprotein B and cholesterol present in the precipitate (r = 0.90, p less than 0.001). These results indicate the presence of a subfraction of the ultracentrifuged high density lipoproteins fraction which is precipitated by concanavalin A and which contains apoprotein B. This fraction is present in varying proportions according to the type of hyperlipoproteinemia, types iib and IV having the greatest amounts. In conclusion, only the concanavalin A precipitation technique results in a separation of apoprotein B-containing and non-apoprotein B-containing lipoproteins. This renders it preferable to ultracentrifugation for determining atherogenicity risks.

Adult↗